10.1021/jo951194h.s001 David Crich David Crich Sanxing Sun Sanxing Sun Jarmila Brunckova Jarmila Brunckova Chemistry of 1-Alkoxy-1-glycosyl Radicals:  The Manno- and Rhamnopyranosyl Series. Inversion of α- to β-Pyranosides and the Fragmentation of Anomeric Radicals American Chemical Society 1996 Photochemical conditions Fragmentation Anomeric Radicals Rhamnopyranosyl Series series abstraction stereoselective quenching side reactions formation 1996-01-26 00:00:00 Journal contribution https://acs.figshare.com/articles/journal_contribution/Chemistry_of_1-Alkoxy-1-glycosyl_Radicals_The_Manno-_and_Rhamnopyranosyl_Series_Inversion_of_-_to_-Pyranosides_and_the_Fragmentation_of_Anomeric_Radicals/3700824 The formation and stereoselective quenching of 1-mannopyranosyl radicals by a tributyltin hydride-mediated intramolecular 1,5-hydrogen abstraction sequence is described. A competing process is 1,4-hydrogen atom abstraction leading principally to glucopyran-2-ulosides. Fragmentation of the anomeric radical resulting in the formation of ring opened products is a problem in certain series. The chemistry is dictated to a considerable extent by the nature of the protecting groups employed with the 4,6-benzylidene series and, for rhamnose, the Ley 3,4-dispiroketal, being particularly susceptible to the 1,4-hydrogen atom abstraction but less to the fragmentation. Photochemical conditions are described, in which these side reactions are practically eliminated, and applied to the inversion of an α- to a β-mannoside in a disaccharide.